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Environmental fate & pathways

Hydrolysis

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Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1939-2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Publication is a rewiew of measured data from 1939 to 1995 in the background of modeling tin in radioactive waste
Justification for type of information:
Modelling from different Sn(II) compounds based on the complete dissoziation of soluble Sn(II) compounds

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
A critical rewiev of thermodynamic data for inorganic tin species
Author:
Séby et al.
Year:
2001
Bibliographic source:
Geochimica et Cosmochimica Acta Vol. 65, 3041-3053, 2001
Reference Type:
study report
Title:
Unnamed
Year:
1981
Reference Type:
publication
Title:
On the role of Sulfate Ion in Acid Tin Methansulfonate Electrolytes
Author:
Martyak et al.
Year:
2006
Bibliographic source:
Galvanotechnik 1/2006 p.46ff

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
not applicable
Remarks:
special methods see box "pronciples of methode if other than guideline"
Principles of method if other than guideline:
methodes used: potentiometry, Difference Pulse Cathodic Stripping Voltammetry, calculation, combination of thermodynamic formation data
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Radiolabelling:
no

Study design

Analytical monitoring:
not specified
Details on sampling:
-
Buffers:
-
Estimation method (if used):
modeling at standard conditions (temperature: 25°C, pressure: 1 bar, ionic strenght: 0) using SIT methodology
Positive controls:
not specified
Negative controls:
not specified

Results and discussion

Preliminary study:
-
Test performance:
-
Transformation products:
yes
Total recovery of test substance (in %)
% Recovery:
ca. 100
St. dev.:
0
pH:
7
Temp.:
25 °C
Duration:
> 1 - < 100 d
Remarks on result:
other: information only to pass tcc, not relevant

Any other information on results incl. tables

Sédy et al. pointed out that in the most studies to high concentrations of tin were used and so polytin complexes were formed. Further Sédy et al. show that there is a different in the species formed in a solution with and without halogeninde.

The values measured under standard conditions (25°C, 1bar)

 

Chemical equilibrium

-log^{m}K°

I (mol L^{-})

Remark

Sn^{2+} + H_{2}O <=> SnOH^{+} + H^{+}

3.8 +/- 0.2

0.1, 0.5, 1.0

Inorganic tin hydrolysis

Sn^{2+} + 2H_{2}O 

<=>

Sn(OH)^{0}_{2} + 2H^{+}

7.8 +/- 0.2

0.1, 0.5, 1.0

Inorganic tin hydrolysis

Sn^{2+} +3H_{2}O 

<=>

SnOH^{-}_{3} + 3H^{+}

-17.5 +/- 0.2

0.1, 0.5, 1.0

Inorganic tin hydrolysis

Sn(OH)_{2}(s)óSn^{2+} + OH^{-}

25.80

0_{corr}

Precipitation Reactions

SnO(s) + H_{2}O  

<=>

Sn^{2+} + OH^{-}

26.24

0_{corr}

Precipitation Reactions

 

The ion interaction coefficients are:

%epsilon

Value (L mol^{-1}

Sn^{2+}, NO_{3}^{-}

0.4 +/- 0.1

SnOH^{+}, NO_{3}^{-}

0.2 +/- 0.1

Sn(OH)_{2}, NO_{3}^{-}

0.3 +/- 0.1

H^{+}, NO_{3}^{-}

0.07 +/- 0.01

 

 

Distribution of various species of tin (II) as a function of pH

 

Sn^{2+} / %

Sn(OH)^{+} / %

Sn(OH)_{2} / %

Sn(OH)_{3}^{-} / %

4.0

30

40

30

0

4.5

7

34

59

0

5.0

2

11

87

0

5.5

0

4

96

0

6.0

0

2

98

0

6.5

0

1

99

0

7.0

0

0

100

0

7.5

0

0

99

1

8.0

0

0

98

2

8.5

0

0

95

5

9.0

0

0

80

20

9.5

0

0

50

50

10.0

0

0

30

70

 

Distribution of various species of tin (II) as a function of pH in present of 10^{-2} mol L^{-} [Cl^{-}]

 

Sn^{2+} / %

SnCl^{+} / %

SnCl_{2} / %

Sn(OH)^{+} / %

Sn(OH)_{2} / %

Sn(OH)_{3}^{-} / %

4.0

27

10

1

35

27

0

4.5

8

3

0

29

60

0

5.0

0

0

0

15

85

0

5.5

0

0

0

5

95

0

6.0

0

0

0

3

97

0

6.5

0

0

0

1

99

0

7.0

0

0

0

0

100

0

7.5

0

0

0

0

99

1

8.0

0

0

0

0

98

2

8.5

0

0

0

0

95

5

9.0

0

0

0

0

80

20

9.5

0

0

0

0

50

50

10.0

0

0

0

0

30

30

 

recovery of data: 95%

Martyak reports for the hydrolysis reaction of stannos sulfate a free energy of %DELTA G = -7.37 kcal/mol and a equilibrium constant of ~1.8 x 10^5.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Tin(II) can be hydrolysed into SnOH^{+}, Sn(OH)_{2} and Sn(OH)^{-}_{3}. In The pH frame according the guideline most of the Sn(II) exists as
Sn(OH)_{2}. The equilibrium constant for the dissioziation logK = 7.8 +/- 0.2 (@20°C)..
Martyak reports for the hydrolysis reaction of stannos sulfate a free energy of %DELTA G = -7.37 kcal/mol and a equilibrium constant of ~1.8 x 10^5.

So the stannous sulfate ist not stable in water. Under alkaline conditions (pH>8 ) changes immediately oxidation state 2 to 4.